Method of and apparatus for determining the consistency of concrete



Oct. 8, 1929. E. H. LICHTENBERG METHOD OF AND APPARATUS FOR DETERMINING THE CONSISTENCY OF CONCRETE Filed July '7, 1926 3 Sheets-Sheet l Oct. 8, 1929. E. H. LICHTENBERG 1,730,893

METHOD bl AND APPARATUS FOR DETERMINING THE CONSISTENCY OF CONCRETE Filed July '7, 1926 3 Sheets-Sheet 2 attozwu p 1929- E. H. LICHTENBERG 1,730,893

METHOD OF AND APPARATUS FOR DETERMINING THE CONSISTENCY OF CONCRETE Filed July '7, 1926 3 Sheets-Sheet 5 Patented Oct. 8, 1929 UNITED STATES PATENT OFFICE ERICK H. LICHTENBERG, OF MILWAUKEE, WISCONSIN, ASSIGNOB TO KOEHBING COM- PANY, OF MILWAUKEE, WISCONSIN, A CORPORATION METHOD OF AND APPARATUS FOR DETERMINING THE CONSISTENCY OF CONCRETE Application filed July 7,

It has become a well known fact in concrete engineering that the water content of cement concrete mixes controls, to a great extent, the strength of concrete in actual construction, and so important is this factor that definite tables of water-cement ratios have been laid down for specified construction work.

In fact, this factor is of so much importance that on all major operations, especially such as Federal or State roadbuilding, constant surveillance is or should be exercised through inspectors of work, who should make tests from time to time, and frequently, to maintain the proper consistency of the mixes. In this way only is it possible to prevent the utilization of too dry or too wet a mix, either of which would materially affect the durability or strength of the construction work.

Difliculty, however, has always been experienced in determining and maintaining the standard consistency with any degree of facility or without waste of time, labor and materials, because up to the present time no very satisfactory test has been devised whereby this consistency factor might be readily controlled.

Those tests which have been employed are more or less effective for laboratory purposes alone, and are not generally applicable to actual working operations. As a matter of fact, so far as I am aware, after many years of experience in the art of concrete mixing, no means or method of determining the consistency of the mixture during the mixing op eration has ever been proposed.

Practically the only standard test for general purposes which has met with recognition today is the so-called slump-test, which involves the taking of the sample from the wet concrete after it has been mixed and allowing it to slump upon a surface. This test is not always uniform under varying admixtures and must be carefully interpreted to produce even fair results.

There is a still further test which has been proposed recently and which is set forth in the patent to Jackson No. 1,576,438, of March 9, 1926, and sometimes referred to as the plate test. Such test of the consistency is 1926. Serial No. 121,030.

made by weighing an amount of wet concrete which Is retained upon a circular plate of a specified diameter when the concrete is depos ted thereon in a standard manner. Here again, it will be observed, the test is carried out subsequent to the mixin operation and naturally it is no more satis actory than the slump-test so far as practicability of application to field control is concerned.

In contra-distinction to this, the instant in vention involves several broad and distinctively novel phases: firstly, a new method for determining the consistency of the concrete during the mixing operations; secondly, the determination of such consistency upon the basis of the impact force exerted upon an mpact receiving member; thirdly, the coordination of a water control with the consistency determining means; and, fourthly, the provision of means for preventing the discharge of the concrete until the proper consistency has been attained, or, from a different aspect, the provision of means to prevent the introduction of excess water until the particular batch being mixed has been discharged.

The principle of my present test method is based upon the observance of the fact that as the water content of the concrete mix increases, the physical condition of the mix changes rapidly and proportionately, so that by the association of an indicating device with a concrete mixing apparatus in such manneras to be acted upon by the material, it can readily be calibrated to determine the proper consistency for the particular work. Since this test is intended to be carried on during the mixing operation, the condition is, therefore, continuously indicated, no delays are lncurred for test purposes, and corrections may be readily made as to the watercement ratio without materially interfering with the operations.

I have herein illustrated, by way of exemplification of the principle, two different 9 methods of consistency tests: (1) that meth 0d based upon the impact force exerted by the wet concrete; and (2) that based upon the inherent resistance of the fluid material to change its form, or what I term the viscosity test; either of these serves as a control when applied to standard mixing apparatus, so that I do not desire to be restricted in myapplication of the principle. Broadly stated, I believe that I am the first to associate with mixing apparatus for use in the field a consistency determining or controlling means, and it is to be understood that I do not wish to be restricted, as regards the details of the arrangements described herein, and illustrated in the accompanying drawings wherein:

Figure 1 is a side elevation of a mixing apparatus embodying my invention, certain parts being broken away and shown in section to disclose the details of construction;

. Figure 2 is a fragmentary elevation showing a modifiedtype of consistency indicator for application to apparatus already in use;

Figure 3 is a fragmentary view, parts being broken away to show a modified form of indicator for use in determining the consistency of the concrete by the viscosity test;

Figure 4 is a detail view of the indicator disclosed in Figure 3;

Figure 5 is a view similar to Figure 1 showing the coordination of the water and discharge controls with the consistency indicator;

Figure 6 is a detail view of the contact members used in connection with the indicator disclosed in Figure 5; and

Figures 7 and 8 are further modified forms of consistency indicators embodying the principle of my invention.

Referring particularly to that form of the apparatus which is illustrated in Figures 1, 2 and 5, A designates the mixing drum of a conventional type of concrete mixer, said drum including the mixing blades B, the pick-up buckets C, and the swing or discharge chute D. E is the supporting frame above which is located the usual water tank F and the water valve G therefor under the control of which the water is delivered to the drum through the pipe H. Figures 2 and 4 of the drawings show a consistency indicator applied to such a mixer in the form of an attachment unit, such as might be employed where the mixer apparatus is not originally designed with this indicator incorporated in its construction, while Figures 1 and 5 disclose applications of the device as a part of the original equipment preferably. So far as the underlying principles are concerned these embodiments are considered to be equivalents.

The indicator unit attachment, however, will first be set forth. Upon the frame E, preferably at the discharge end of the drum, is pivotally secured at 1 an arm 2, the inner end of which extends within the adjacent drum opening and terminates in an impact receiving plate 3. This plate is of a predetermined operative area and is either horizontal- 1y disposed or arranged at an incline, as shown in the drawings to be the preferred manner, so as to lie in the path of movement of the mix as it drops from one pick-up bucket to a lower bucket. The opposite end of the arm 2 is formed with a pointer 4 which cooperates with a calibrated scale member 5, the indicia of which will determine the state of consistency in the operation of the device. A counterbalanee or tensioning means is provided as an adjunct of the arm 2, in this instance consisting of a rod 6 connected by the link 7 to the arm and carrying weights 8 and spring 9, the tensioning naturally preventing undesirable vibratory oscillations of the indicator during mixing operation.

The operation of this simple form of the apparatus, which it will be recalled can be readily applied to any ordinary mixer already in use, will be as follows: The dry materials are charged into the drum by the skip in the usual manner and the water is simultaneously admitted as customary. The materials under these conditions take up a sufficient amount of water to cause the particles to adhere to each other but not necessarily enough to constitute a good mix for the par pose at hand. Under these circumstances as the drum rotates the aggregates are lifted by the buckets and in dropping therefrom impinge upon the (plate 3 of the arm 2. In this comparatively ry state of the initial mixing period the impact causes the arm to descend the maximum degree, but as the water content increases and the mix becomes wetter, the arm gradually rises until the pointer 4 approaches the mark of the scale 5 which has previously been calibrated to indicate that the proper consistency has been reached. The operator then swings the chute D to discharge position and the contents are discharged in the customary manner. Natural- 1y, observation ofthe indicator as hereinbefore set forth will prevent the incorporation of too great an amount of water, the supply of which is cut off manually or otherwise at the proper time in the course of the mixing operation. In this way each batch will conform inconsistency, which is determined from the impact force of the mix itself in the mixing operation, and no delay for tests is incurred. It is to be understood that the pointer is normally on the too wet side of the zero mark of the scale and in case the materials are charged into the drum in an absolutely dry condition and the water is subsequently admitted, it is obvious that the impact of the dry materials on the plate 3 will not be suflicient to move the pointer from the too wet position to the zero point or to the too dry side thereof. The pointer in this case will indicate too wet until suflicient moisture has been mixed with the materials to cause the particles to adhere to each other. When the state of adherence-is reached how- 1,1eo,sea

ever, the pointer will pass to thetoo dryside. As the liquid contents increases this adherence of the particles will grow less tenacious and the pointer will move toward the too wet side and when the zero point is reached, will indicate the time for discharge of the aggregate in the manneras indicated above. In this latter case the first phase of the movement of the pointer to the too wet side of the scale will be ignored and only considered after the pointer has once passed to the too dry side.

It will, of course, be understood that while I have described an indicator means of the visual. type herein, it is within the purview of the invention to employ an audible alarm 1n conjunction with this indicator when desired, this being a matter of expediency and therefore not herein illustrated.

Passing now to that form of the device shown in Figures 3 and 4, the indicator arm 2 .is modified to the extent which will enable the plate 3 thereof to occupy a position near the bottom of the drum in the sump. As the water content of the mix changes, the viscosity changes, and in the rotation of the drum the pressure against the blade 3 causes the pointer 4' to move in relation to the scale 5. In this construction-the weight 8' and spring 9 act as counterbalance means and tend to restore the indicator to normal moperative position.

With the foregoing principles in view, the further adaptation of this invention to the regular mixer construction will readily be understood by reference to Figure 1. In this arrangement the discharge chute D 1s employed to perform the function of the plate 3 on an end of the indicator arm. The d scharge chute is of course disposed in its mixing position in Figure 1, the contents of the drum during rotation falling thereupon. At one side of this chute a pin D projects beneath the indicator arm 2 which is normally held in coacting relation by the action of the Weight 8 and spring 9. It will be noted that the connecting link 10 through which the chute is tilted is formed with a closed slot 11, thereby providing for relative movement of the chute in relation to the link. This freedom of movement enables the consistency test to be carried out by the indicator.

During the initial mixing operation, when the mix is still too dry, the inner end of the chute under the,impact of the falling material descends, as hereinbefore set forth, the pointer 4* indicating on the scale 5 the dry state of the mix. As the water content increases the force of the impact correspondingly decreases and the inner end of the chute tends to ascend, transmitting such motion to the pointer which moves toward zero or the point indicating proper consistency. The water supply is then cut-off at the proper time and then the chute is swung over to discharge position by the operator in the usual manner.

So long as the operator of the mixer is observant of the conditions of the mix as indicated by the indicator device, the operation may be carried'out with the apparatus hereinbefore described very advantageously, but it has been my aim to eliminate as far as possible the human element and to' make the apparatus function automatically or compulsorily, as described. This brin me to the adaptation of the invention disc osed in Figure 5 which embodies all of the features of that form shown in Figure 1, with the addition of the automatic water and discharge controls.

In connection with the latter, the indicator device is slightly modified to provide for the connection thereto of the link 12 which through the crank. 13 and the rod 14 transmits motion to the water valve 15. Thus as the indicator member or pointer is shifted toward the proper consistency point, the water valve is turned through the pressure exerted by the weight 8 and spring 9 and the supply cut off at the predetermined moment, whereupon the discharge chute may be shifted to discharge position. To preclude the possibility of the discharge chute being shifted before the proper consistency of the mix has been reached, I provide a locking means which operates to lock the chute against being swung to discharge position until the consistency is substantially correct. For this purpose a pawl 16 is pivotally mounted upon a bracket 17 in position to normally engage with the extension 18 of the crank arm 19 when the chute is in the mixing position. The spring actuated core of a solenoid 20 is connected to the pawl 16 and said solenoid is included in an electric circuit 21 leading to the adjustable contact 22 mounted upon and insulated from the scale segment 5. The pointer 4 of the indicator member carries a yieldable contact 23 grounded on the frame and arranged to coact with the contact 22 in the movement of the indicator member to close the circuit, thereby displacing the pawl 16 from the path of movement of the element 18. Immediately, under the action of the spring 2 1, the chute D is swung to discharge position. In this, or a similar manner, the proper consistency of the mix must be attained before the batch can be discharged so that I have, in conjunction with a consistency determining means, a control for the discharge action.

At this point it may be well to note that it is well known in the art now to employ a control means which insures that the contents of the drum shall be subjected to a predetermined period of mixing action. Such an arrangement is quite valuable of course but it does not insure that the proper proportions of ingredients are introduced into the drum, speaking with reference to the water cement ratio. However, simply stated, such is the function of this invention.

In further detail, it will be understood that by the adjustment of the contact member 22 on the scale 5, the varying consistency of the mix for different characters of cement work mtiy be taken care of.

n Figure 6 I have shown in detail the type of contacts 22 and 23 employed herein, the last mentioned being a one-way acting contact so far as effecting the closing of the electric circuit is concerned. For this purpose one side of the contact is formed of insulating material so that on the return movement of the indicator the solenoid 20 will not be actuated to release the pawl 16. This arrangement is subject to modification, as are also the other details herein disclosed, without departing from the spirit of the invention.

In this connection it is obvious that the automatic actuation of the chute by the spring 24 may be dispensed with if desired and yetthe discharge of the drum by manual or other means would be controlled by the consistency of the contents in view of the locking action of the pawl 16.

Referring now to the modified form of indicator device shown in Figure 7, 3 is an impact receiving plate or member carried by a stem 3" of insulating material and yieldably mounted for vertical movements in the casing 25 at the end of the bracket arm 26. At its lower end the stem is reduced and surrounded by a spring 27, the tension of which may be adjusted by the nut 28 so as to take care of the variations in the consistency required for different works. Intermediate its length the stem carries a circuit closing collar 29 which is adapted to coact with the spaced contacts 30, 30, at one side, and the common contact 31 at the other side to which the leads from a battery 30 are connected.

In the circuits are arranged signal members or flags 33, 33, carried by the cores of the respective solenoids a: and 1 these flags appearing at their associated windows 34 in the easing 35 when the solenoids are energized in the movement of the member 3 under the action produced by the impact of the cement mixture thereon.

Figure 8 is simply a further adaptation of this idea used in Figure 7, as designed for either a liquid medium or air. The medium is contained in the collapsible head 25' beneath the impact plates 3 and is forced through the conduit 26 to the indicator tube 35 in which is mounted a colored ball float, the position of which indicates the state of the consistency.

Other modifications might readily be devised for producing the same result and are intended to be'broadly comprehended within the scope of this invention.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. The method of determining the consistency of concrete, which consists in causing the mix of concrete to move at a predetermined rate, placing in the ath of the moving concrete an indicator member having a given operative area, and movable under the action of the movin concrete and determining the consistency of the concrete from the resistance offered by said member.

2. The method of determining the consistency of concrete, which consists in disposing a yieldable indicator member of a given operative area in the path of movement of the concrete during the mixing operation, ascertaining the deflection of said member, and determining the consistency of the concrete from said deflection.

3. The method of determining the consistency of concrete, which consists in measuring the impact force of a stream of wet concrete mix by a member movable under the action of the stream of concrete, and determining from the impact the consistency of the concrete.

4. The method of determining the consistency of concrete which consists in subjecting an indicator device to the impact force of a stream of the concrete mix, and determining from the deflection of said device the consistency of the concrete. l

5. The method of determining the consistency of concrete, which consists in causing a mixing action of the aggregate materials and water, causing such admixture to impinge upon an indicator incident to this mixing action, and determining from said indicator the consistency of the concrete.

6. The method of determining the consist ency of concrete, which consists in revolvmg a receptacle in which a mixture of the ag gregate materials and water are placed to produce a mixing action and elevation and fall of said materials incident thereto, disposlng in the path of fall of the materials an indicator device, the deflection of which determines the impact force, and determining from such deflection the consistency of the concrete.

7. The method of determining the consistency of concrete, which consists in causing a mixing action of the aggregate materials; supplying water thereto; subjecting an indicator device including a member movable under the mixing action of the concrete, the deflection of which indicates the water content, to the moving materials; and cutting off the supply of water when a predetermined amount of the same, as indicated by the device, has been incorporated.

8. The method of determining the consistency of concrete which consists in causing a m1x1ng action of the aggregate materials; supplying water thereto; subjecting an indicator device including a member movable under the mixing action of the concrete, the deflection of WlllCll indicates the water content, to the moving materials; and maintaining the mixing action until the indicator device indicates the proper water-content ratio has been reached.

9. The method of determining the consistency of concrete, which consists in causing a mixing action of the aggregate materials; supplying water thereto; subjecting an indicator device, the deflection of which indi cates the water content, to the moving materials; cutting off the supply of water when a predetermined amount of the same, as 1nd1- cated by the device, has been incorporated; and maintaining the mixing action until the indicator device indicates the proper watercontent ratio has been reached.

10. The method of determining the consistency of concrete, which consists in cansing the mixing action of the aggregate materials, supplying water thereto under the control of a consistency-determining means, and preventing admission of excess water supply when the proper consistency has been reached.

11. The combination with a concrete mixer, of a consistency indicator including a member movable under mixing action of the m1xture handled by the mixer.

12. The combination with a concrete mixer, of a consistency indicator including a member movable by contact with the mix incident to mixing action.

13. The combination with a concrete mixer of consistency determining means, mounted in the path of movement of the mix, and oper' able incident to admixture of the water to the aggregate of the mix to indicate the consistency thereof.

14. In concrete mixing apparatus, the combination with a receptacle to receive the mix and a mixing element therein, of consistency determining means associated therewith, in cluding a movable member so disposed 1n relation to the receptacle as to be acted upon by the mix, and an indicator operable by sald movable member.

15. In concrete mixing apparatus, the combination with a receptacle to receive the mix and a mixing element therein, of consistency determining means associated therewith, 1ncluding a movable member disposable in one position to indicate the consistency of the mix and in another position toeiiect discharge of the same.

16. In concrete mixing apparatus, the combination with a receptacle to receive the mix, and a mixing element therein, of consistency determining means associated therewith 1ncluding a movable member so dlsposed 1n the receptacle as to be acted upon by the mix, and an indicator operable by said movable member, said movable member being constructed to change the path of movement of the mix.

17. In concrete mixing apparatus, the combination with a receptacle to receive the mix, of consistency determining means associated therewith, including a movable chute member extending within the receptacle in position to be impinged by the mix, and an indicator device therefor.

18. In concrete mixing apparatus, the combination with a mixer .receptacle, and discharge controlling means therefor, of consistency determining means operable from said discharge control means. I

19. In concrete mixing apparatus, the combination with a mixer receptacle, and discharge controlling means therefor, of consistency determining means operable from said discharge control means, and means for preventing the discharge of the mix until the predetermined consistency has been reached.

20. In concrete mixing apparatus, the combination with a mixer receptacle and discharge controlling means thereforgof consistency determining means operable from said discharge control means, and means for preventing discharge operation of said control means under the control of said consistency determining means.

21. In concrete mixing apparatus, the combination of a mixer, consistency determining means associated therewith, and means for effecting discharge of the contents of the mixer under the control of said consitency determining means.

22. In concrete mixing apparatus, the combination of a mixer complete in itself, separate consistency determining means associated therewith, and means for maintaining the mixing action of the contents until the desired consistency has been reached.

23. In concrete mixing apparatus, the combination of a mixer, water supply means therefor including a cut-off valve, a consistency indicator associated with said mixer, a discharge chute for actuating said indicator, and locking means for preventing movement of the chute into discharge position controlled by said indicator.

24. In a concrete mixing apparatus, the combination of a mixer, water supply means therefor including a cut-off valve, a consistency indicator associated with said mixer, a discharge chute, locking means for preventing movement of the discharge chute until a predetermined consistency of the mix has been reached, and means operable from the indicator for operating the cut-off valve and the locking means.

25. In concrete mixing apparatus, the combination of a mixer, water supply means therefor, and consistency determining means separate from and associated with the mixer and operable to control the water supply means.

26. In concrete mixing apparatus, the combination of a mixer, water supply means therefor, and consistency determining means separate from and associated with the mixer and means intermediate the last named means and the water supply means for discontinuing the delivery of water when a predetermined consistency of the mix had been reached.

27. In concrete mixing apparatus, the combination of a mixer complete in itself, water supply means therefor, and independent con- 10 sistency indicator associated with the mixer,

means for controlling discharge of the contents of the mixer, and means for automatically discontinuing the water supply and discharging of the mix when the consistency 5 thereof has been reached.

28. In concrete mixing apparatus, the combination of a mixer complete in itself, water supply means therefor including a cut-off valve, a consistency indicator separate from and associated with said mixer, and an operating connection between the indicator and the valve.

In testimony whereof I afi'ix my signature.

ERICH H. LICHTENBERG. 

